Development of steamflow meter to be attached to the outside of a tube using a circumferential heater

Abstract

Recently, necessity of energy saving is more increasing in the industrial field with relation to energy cost increase. Measurement of steam flow rate is indispensable for a performance diagnosis and an energy solution in facilities such as factories and power plants. However, a sensor installation for steam flow is generally difficult. Because the industrial facilities needs to be out of operation temporarily, in the case of installation of conventional flowmeter such as orifice type and vortex type. And steam pipes are necessary to be cut for the installation. Accordingly, clamp-on type steam flowmeter, of which installation does not require pipe-cutting, is hoped to be developed. Ultrasonic sensor has certain degree of possibility for steam flow measurement. On the other hand, there are such problems as ultrasonic inlet to a pipe and operational condition of temperature, to be solved. Therefore, we devised “heater method” for steam flow measurement. A circumferential heater is attached to the outside of a tube. Then, axial temperature distribution on the tube outside is measured. Steam velocity is analyzed on the basis of the temperature distribution, considering heat transmission in the pipe and thermal conductivity in steel pipe. The sensor is heat-resistant and possible to measure high temperature fluid, because it is comprised of the heater, thermocouples and insulator. It is necessary to solve physical phenomenon such as temperature boundary layer and thermal conductivity in the pipe in case of thin area heating, to develop the method. This paper reports air and steam flow rate measurements by the heater method, and comparison between analyzed fluid velocity and reference fluid velocity.